Mechanism for a timepiece having a plurality of time display

ABSTRACT

A snap mechanism for a timepiece having a plurality of time displays in which either a first hour wheel or a second hour wheel is provided with saw teeth, and between the first and second hour wheels there are interposed a sliding member having saw teeth which are engaged with the saw teeth on the particular hour wheel and a spring pressing the sliding member so that the saw teeth are in engagement. The first and second hour wheels, sliding member and spring are assembled as a self-contained unit.

United States Patent 1191 Ikegami Jan. 15, 1974 MECHANISM FOR A TIMEPIECE HAVING A PLURALITY OF TIME DISPLAY Inventor:

Toshimasa Ikegami, Chino, Japan Kabushiki Kaisha Suwa Seikosha, Tokyo, Japan 22 Filed: Jan. 10, 1973 211 Appl. No.: 322,493

Assignee:

Foreign Application Iriority Data Jan. 13,1972 Japan 47/6986 58/425, 58/855 9114b 19 2 2 G04b 27/00 {1 131655251611 sit/4215 44353 [56} References Cited UNITED STATES PATENTS 10/1971 Bore! 58/425 7/1972 Gasser et a1. 58/855 3,695,035 10/1972 Cleusix ..58/42.5

Primary Examiner-Richard B. Wilkinson Assistant Examiner-Edith C. S. Jackmon Attorney-Eric H. Waters et a1.

ABSTRACT A snap mechanism for a timepiece having a plurality of time displays in which either a first hour wheel or a second hour wheel is provided with saw teeth, and between the first and second hour wheels there are interposed a sliding member having saw teeth which are engaged with the saw teeth on the particular hour wheel and a spring pressing the sliding member so that the saw teeth are in engagement. The first and second hour wheels, sliding member and spring are assembled as a self-contained unit.

10 Claims, 1 Drawing Figure MECHANISM FOR A TIMEPIECE HAVING A PLURALITY OF TIME DISPLAY BACKGROUND 1. Field of the Invention This invention relates to a snap or click mechanism for a timepiece having a plurality of time displays and more particularly to such a mechanism in which the time displays can be relatively adjusted.

2. Prior Art A conventional click mechanism for a timepiece havin g a plurality of time displays is characterized by a first hour wheel having a number of projections equal to 12 or multiples of 12 and a second hour wheel having a number of recesses equal to 12 or multiples of 12, the hour wheels and parts, such as a dial, having an elastic member interposed therebetween, the click mechanism being adapted to locate said first and second hour wheels relatively. In another arrangement, the same number of gears as above are coupled to a first hour wheel and a jumping member fixed to the second hour wheel locates said first and second hour wheel relatively.

The first arrangement has the deficiency that since the elastic member engaged with the first and second hour wheels is interposed between them, a member outside the wheels, such as a dial, a gear train, or the like is subjected to a strong load when the hands are driven due to the braking action of said elastic member. Consequently, the mechanism cannot be utilized in a timepiece having a small driving force, such as an electronic timepiece or a womens timepiece. Furthermore, since between one recess and its neighboring recess there exists a portion where the force is balanced, and only a relatively weak click force is transmitted to a winding crown when a projection is located into the neighboring recess and mistaken correction sometimes occurs. Moreover, as the projection is made to climb out of a recess and be located into the neighboring recess, a second hour hand to be corrected is moved up and down. As the space for the jumping member is very small, the length of the spring may be insufficient, and there are instances in which fatigue is imposed on the spring, and if the spring becomes fatigued, the first hour hand and the second hour hand may be shifted to produce an indicating error; Furthermore, since only one jumping member is provided, one of the first and second hour wheels may be pressed at an angle in the gap therebetween and cause scarring, stopping, and the like of the hands against the dial face. Furthermore, even if this is prevented, there remains the further deficiencies that assembly requires skill and the timepiece will be thick. On the other hand, though many other timepieces having a plurality of time displays are known, they are not popular because they are thick, expensive and complicated to use, due to their relatively large number of parts.

SUMMARY OF THE INVENTION An object of the invention is to provide a timepiece having a plurality of time displays in which the abovementioned deficiencies are avoided.

The timepiece of the invention is characterized in that either a first hour wheel or a second hour wheel is provided with saw teeth and between said first and second hour wheels there are interposed a sliding member and a spring. The sliding member is able to slide up .and

BRIEF DESCRIPTION OF THE DRAWING The sole FIGURE of the drawing is an exploded view partly in section, of a click or snap mechanism by which plural displays may be relatively adjusted.

DETAILED DESCRIPTION Referring to the drawing, the mechanism comprises an hour wheel stem 7 fixed to a first hour wheel gear 1. At first hour hand (not shown) is supported by the hour wheel stem 7. An upper ratchet wheel 5 is fixed to a second hour wheel gear 6, the wheel 5 and gear 6 forming a second hour wheel 4. A second hour hand (not shown) is supported by the upper ratchet wheel 5.

A sliding member 3 having saw teeth is slidably mounted for up and down movement along a sleeve 9 of the first hour wheel gear 1, said sleeve 9 receiving the stem 7. The member 3 is provided with side recesses 3a which are engaged with inner projections 21; of a ring-shaped ratchet spring 2. The ratchet spring 2 has projecting ends 2a which are fitted in apertures la of the first hour wheel gear 1 and fix the angular position of the sliding member 3 and the first hour wheel gear 1. A first hour wheel is formed by the first hour wheel gear 1, the sliding member 3, the ratchet spring 2 and the hour wheel stem 7.

When the hands are driven in the normal course of operation, the upper ratchet wheel 5 is engaged with the sliding member 3, so the first hour wheel and the second hour wheel 4 drive their hands in' concert. When the second hour hand is to be corrected, the second hour wheel 4 is rotated by a second hour hand correcting wheel 8 from the outside, using a correcting mechanism. At this time, as the upper ratchet wheel 5 supporting the second hour hand is prevented from moving upwards by its engagement with the hour wheel stem 7 fixed to the first hour wheel gear 1, the upper ratchet wheel 5 is rotated while the sliding member 3 and the ratchet spring 2 move downwards, and is located in the next tooth by the spring force of the ratchet spring 2. The action is repeated until the second hour hand is corrected with respect to the first hour 1 hand.

As mentioned above, utilization of a snap or click mechanism which applies electric pressure from the inside by the spring 2, for controlling the mutual position of the two hands, to the sliding member controlled by the first hour wheel in the rotating direction and to the upper ratchet wheel fixed to the second hour wheel, so that the two are located relatively, makes it possible for the gear train to suffer no additional load. Hence, this mechanism can be used in a timepiece having a small driving force, such as an electronic timepiece or a womens timepiece. Furthermore, since the spring is symmetrical and its ends are free, the inclination of the second hour hand is eliminated. Moreover, the number of assembly operations and the number of parts are reduced due to a minimum, so that a low price is ensured. Furthermore, as the first and second hour wheels are formed as a self-contained unit, a timepiece having a correcting mechanism can be easily reformed for one having a plurality of time displays only by exchanging a few parts. Moreover, since the spring is inserted inside the hour wheel, deformation of the spring at the time of dismantling and assembly is prevented, and the magnitude of the spring force can be stabilized as the parts which affect the spring force are relatively few.

What is claimed is:

1. An adjustment mechanism for a timepiece having a plurality of time displays, said mechanism comprising first and second hour wheels coaxially mounted in spaced relation, one of said hour wheels being provided with saw teeth, a sliding member interposed between said hour wheels for axial movement in opposite directions, said sliding member having saw teeth engaged with the saw teeth on said one hour wheel, and spring means also interposed between said hour wheels and acting on said sliding member to urge the saw teeth thereof into engagement with the saw teeth on said one hour wheel such that when said one hour wheel is turned relative to the other hour wheel said one hour wheel will move step-by-step as each of the saw teeth of the hour wheel engage successive saw teeth of the sliding member, said spring means undergoing deformation to permit the relative rotation of the hour wheels.

2. A mechanism as claimed in claim 1 wherein said sliding member and spring means include means for coupling the same together for common rotation.

3. A mechanism as claimed in claim 2 wherein the means which couples the sliding member and spring means for common rotation comprises projections on the spring means and recesses in the sliding member receiving said projections.

4. A mechanism as claimed in claim 2 wherein said spring means and the other said hour wheel include means for coupling the same together for common rotation.

5. A mechanism as claimed in claim 4 wherein the means which couples the spring means and the other said hour wheel for common rotation comprises projecting end portions on said spring means and apertures in said other hour wheel receiving said projecting end portions.

6. A mechanism as claimed in claim 4 wherein said spring means comprises a spring member of symmetrical construction.

7. A mechanism as claimed in claim 6 wherein said spring member has a ring shape, said means which couples the sliding member and spring means for common rotation comprising inner projections on the spring member and recesses in the sliding member receiving said projections, said means which couples the spring means and the other hour wheel for common rotation comprising outer projections on the spring member and apertures in the other hour wheel receiving said outer projections.

8. A mechanism as claimed in claim 7 comprising a stem secured in said other hour wheel for driving the same in rotation therwith, said one hour wheel being loosely mounted in said stem and rotating therewith as said stem is turned.

9. A mechanism as claimed in claim 8 comprising means coupled to said one hour wheel to rotate the same on said stern and to produce relative rotation between said hour wheels.

10. A mechanism as claimed in claim 9 wherein said first and second hour wheels comprise gear members. 

1. An adjustment mechanism for a timepiece having a plurality of time displays, said mechanism comprising first and second hour wheels coaxially mounted in spaced relation, one of said hour wheels being provided with saw teeth, a sliding member interposed between said hour wheels for axial movement in opposite directions, said sliding member having saw teeth engaged with the saw teeth on said one hour wheel, and spring means also interposed between said hour wheels and acting on said sliding member to urge the saw teeth thereof into engagement with the saw teeth on said one hour wheel such that when said one hour wheel is turned relative to the other hour wheel said one hour wheel will move step-by-step as each of the saw teeth of the hour wheel engage successive saw teeth of the sliding member, said spring means undergoing deformation to permit the relative rotation of the hour wheels.
 2. A mechanism as claimed in claim 1 wherein said sliding member and spring means include means for coupling the same together for common rotation.
 3. A mechanism as claimed in claim 2 wherein the means which couples the sliding member and spring means for common rotation comprises projections on the spring means and recesses in the sliding member receiving said projections.
 4. A mechanism as claimed in claim 2 wherein said spring means and the other said hour wheel include means for coupling the same together for common rotation.
 5. A mechanism as claimed in claim 4 wherein the means which couples the spring means and the other said hour wheel for common rotation comprises projecting end portions on said spring means and apertures in said other hour wheel receiving said projecting end portions.
 6. A mechanism as claimed in claim 4 wherein said spring means comprises a spring member of symmetrical construction.
 7. A mechanism as claimed in claim 6 wherein said spring member has a ring shape, said means which couples the sliding member and spring means for common rotation comprising inner projections on the spring member and recesses in the sliding member receiving said projections, said means which couples the spring means and the other hour wheel for common rotation comprising outer projections on the spring member and apertures in the other hour wheel receiving said outer projections.
 8. A mechanism as claimed in claim 7 comprising a stem secured in said other hour wheel for driving the same in rotation therwith, said one hour wheel being loosely mounted in said stem and rotating therewith as said stem is turned.
 9. A mechanism as claimed in claim 8 comprising means coupled to said one hour wheel to rotate the same on said stem and to produce relative rotation between said hour wheels.
 10. A mechanism as claimed in claim 9 wherein said first and second hour wheels comprise gear members. 